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Luteinizing Hormone (Blood)

Does this test have other names?

LH

What is this test?

This test measures the level of luteinizing hormone (LH) in your blood.

LH is made by your pituitary gland. In women, the pituitary sends out LH during the ovulation part of the menstrual cycle. This tells the ovaries to release a mature egg. In men, LH causes the testes to make testosterone.

This test can help find out the cause of fertility problems in both men and women. A higher LH level can help a woman find out the point in her cycle when it's best to try to conceive.

This test can also help diagnose a pituitary gland disorder.

Why do I need this test?

You may need this test if you are infertile and your healthcare provider needs to find out the cause. You may also have this test if you have symptoms of a pituitary disorder, such as prolactinoma, or a benign tumor in the pituitary gland. Symptoms include:

Impotence or lower sex drive in men

Lactation in women who aren't pregnant or nursing

You may also have this test if you are having irregular menstrual periods.

What other tests might I have along with this test?

Your healthcare provider may also order other tests for infertility. If you're a man, your provider may order a semen analysis, genetic tests, and other blood tests to measure different hormones. If you're a woman, your provider may order other hormone-level blood tests and basal body temperature testing. He or she may also order a pelvic ultrasound and a hysteroscopy to look at the inside of your uterus.

What do my test results mean?

Test results may vary depending on your age, gender, health history, the method used for the test, and other things. Your test results may not mean you have a problem. Ask your healthcare provider what your test results mean for you.

Results are given in international units per liter (IU/L). The normal range for a woman varies, depending on her menstrual cycle. Here are normal ranges:

Men: 1.24 to 7.8 IU/L

Women, follicular phase of menstrual cycle: 1.68 to 15 IU/L

Women, midcycle peak: 21.9 to 56.6 IU/L

Women, luteal phase: 0.61 to 16.3 IU/L

Women, postmenopausal: 14.2 to 52.3 IU/L

Girls, ages 1 to 10 years: 0.03 to 3.9 IU/L

If you're a woman, abnormally high levels of LH during nonovulatory times in your menstrual cycle may mean you are in menopause. It may also mean that you have a pituitary disorder or polycystic ovary syndrome. Low levels of LH may mean you have a pituitary disorder, anorexia, malnutrition, or are under stress.

If you're a man, abnormally high LH levels along with low levels of testosterone may mean that your testicles aren't responding to LH's signal to make more testosterone. Low levels of LH may mean that your pituitary gland isn't making enough LH. That can lead to too little testosterone production.

How is this test done?

The test is done with a blood sample. A needle is used to draw blood from a vein in your arm or hand.

Does this test pose any risks?

Having a blood test with a needle carries some risks. These include bleeding, infection, bruising, and feeling lightheaded. When the needle pricks your arm or hand, you may feel a slight sting or pain. Afterward, the site may be sore.

What might affect my test results?

If you're a woman, your results will vary depending on what day in your menstrual cycle the test is done.

How do I get ready for this test?

You don't need to prepare for this test. Be sure your healthcare provider knows about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any illicit drugs you may use.